1. Field of the Invention
The present invention relates to printed circuit boards and, particularly, to a flexible printed circuit board with excellent flexibility.
2. Description of Related Art
Flexible printed circuit boards (FPCBs) are widely used in portable electronic devices such as mobile phones. Mobile phones, especially foldable mobile phones and sliding mobile phones, require flexible printed circuit board that can be repeatedly bent and re-bent.
Referring to FIG. 5, a typical flexible printed circuit board 10 is shown. The flexible printed circuit board 10 includes a flexible base film 11 and a signal trace pattern 12 formed on the flexible base film 11. When the flexible printed circuit board 10 is bent, shearing stresses in the flexible base film 11 can affect the signal trace pattern 12. In practice, the flexible printed circuit board 10 may be bent repeatedly or even over-bent, and thus the signal trace pattern 12 may be exposed to shearing stresses. This repeated exposure to shearing stresses can cause the signal trace pattern 12 to malfunction or become damaged.
Therefore, a flexible printed circuit board 10 with excellent flexibility performance is desired.